What does this code do?

I don't think the answer to this questions is "comment your code", it's "give your functions meaning full names".

Commenting is great, but you need to know how the program is put using meaningful function and method names not only when they are declared, but also when they are called/passed.

I use comments when I've taken a non-obvious path with the code, and I explain why in comments. I think that is what comments are for.